He said mortgage lenders regarded the Birmingham to London High Speed 2 rail link as a risk to property values.
Whilst none had issued formal guidance, it has been rumoured some lenders told surveyors verbally their desire to prevent exposure to the risk of negative equity.
Sexton said: “No lender has or would ask a valuer to produce a lower property value than actual. They are however seeking assurances that the valuers they work with are aware of the issue so that any impact on prices is being taken account of when valuers produce their reports.
“Lenders would be concerned if they had significant numbers of properties in mortgage which were affected by the route as it could push them into negative equity situations.”
Sexton added that the difficulty for any surveyor was that there was little information about the likely environmental impact.
He said:“The fact that the rail link is planned to operate at speeds substantially in excess of the Channel Tunnel Rail Link and European high speed rail lines means that the noise and vibration it is likely to cause are unfamiliar.”
Sexton added that when the project was complete it was likely that sales volumes and prices would recover but the effect on property values would depend upon local topology, for example how noise travelled and the visual impact of the railway would be on the area.
The government will serve compulsory purchase orders on properties it considers most affected but not until at least 2015.
It said it would pay open market values as if unaffected by the HS2 scheme, plus a home loss repayment of up to £47,000.
Trevor Kent, Buckinghamshire-based estate agents, called the affected area “a black hole, a corridor of uncertainty” following the announcement by the government on HS2.
He said: “This hammer-blow has fundamentally affected property owners and occupiers from London to Birmingham within sight, sound or path of the route.”
Kent has called for the establishment of an independent quango with funds to immediately get to grips with residential and commercial property owners and tenants along the route that are unable to sell at any price over the next few years.
Meanwhile the Royal Institute of Chartered Surveyors said it supported the HS2 scheme.
Jeremy Blackburn, head of policy at RICS, said: “RICS supports the development of the high speed rail and welcomes the government’s commitment to deliver the HS2 scheme in England.
“It has huge potential to contribute to economic growth as well as lowering carbon emissions and expanding the capacity and speed of the UK’s transport network.”
Blackburn added that the impact of HS2 on communities along the route was a critical issue and every practical step must be taken to minimise disruption and negative impacts.
He said: “Adequate compensation procedures must be in place for those affected by the line and RICS is willing to work with the government to advise on dispute resolution and compulsory purchase issues.”
Sexton also added that despite the negative consequences for many families there are some benefits from HS2.
He said: “A high speed transport link is a desirable amenity, which will deliver an economic boost, so properties at the end of the lines will likely see their values rise – we saw that in Kent with HS1. Investors and commuters will be falling over each other to snap them up, particularly in Birmingham.”
